1. Field of the Invention
The present invention relates to a processing method using an optical beam such as a laser beam and an energy beam such as of a charged particle, and a processing apparatus, utilizing the beam, more particularly, to a processing method for processing objects such as a resin, ceramic, metal and photolithographic photosensitive layer to drilling, half-etching, surface treatment and exposure to a photoresist using an energy beam such as a laser beam emitted from a CO2 laser, YAG laser or excimer laser.
2. Description of the Related Art
The CO2 laser (at infrared region of from 9 to 11 xcexcm) and YAG laser (at near-infrared region of 1.064 xcexcm) that are currently versatile for industrial application have been used mainly in cutting and welding of processing objects (workpiece or xe2x80x9cworkxe2x80x9d) because of their heat-melt capability. The processing method using such long-wavelength lasers is known as a heat-processing method taking advantage of heating induced by the laser beam.
Processing of the work using the excimer laser having a very short wavelength (193, 248, 308 and 351 nm) is classified as a non-heating processing for processing the work by taking advantage of a photochemical effect through a photochemical reaction induced by the laser beam, enabling to process the work with a superior processing accuracy to the heat-processing.
In the processing method using the excimer laser having such short wavelength, ceramics such silicon nitride, alumina, SiC and TiC, and synthetic resins such as polyimide, polyester, epoxy resin and polycarbonate are processed without melting with heat. In this method, intermolecular bonds are cleaved by exciting respective molecules in the polymer successively from the surface during the irradiation with the laser beam, which allows the molecules in a solid state to be scatter directly. This processing method is usually called an ablation processing, and makes it possible to achieve a more precise processing compared with the processing method using the CO2 laser and YAG laser.
As a work processing method taking advantage of characteristics of such an excimer laser is a half-etching processing by which the surface of a relatively thick resin plate is drilled to a given depth. The half-etching processing using the excimer laser is utilized as a processing method for thinning the work at the minute hole portion of the printing mask in order for a paste such as a cream solder, or an ink for use in minute holes formed on the printing mask, to be readily discharged.
The laser beam emitted from the laser mentioned above is usually focused to have a beam spot shape of about 2 mm square on the processing surface of the work after passing through an aperture or a condenser. Therefore, the work has to be processed by displacing relative to the laser beam when the length of an etching groove or the size of a hole to be formed on the work, or the length of a cutting or welding site of the work, is larger than the beam spot of the laser beam.
Accordingly, a table with an approximately horizontal mounting face for mounting the work is usually placed on a X-Y table which is capable of displacing of traveling the work mounting face along the X-Y directions. The X-Y table is provided so as to travel along the X-Y directions, to thereby for the work mounted on the mounting table to travel relative to the laser beam.
A driving motor such as a servomotor or a stepping motor is used for the driving source of the X-Y table equipped with the mounting table in the conventional processing apparatus using the aforementioned laser beam. It has been known that a rotational velocity of this driving motor is not immediately increased to a given speed Sm, but gradually accelerated for a period of time t1 after a driving signal is outputted from the driving circuit at t0 for initiating the rotation, as shown in FIG. 7. For halting the X-Y table, on the other hand, rotation of the driving motor is not allowed to stop instantaneously but has to be decelerated starting at t2 from the given speed Sm, to finally stop the rotation at t3.
Accordingly, the traveling velocity of the mounting table on the X-Y table driven with the driving motor is gradually accelerated, approximately by the same way as in the rotational velocity of the driving motor, during a time interval of from t0 to t1 after initiation of travel and is gradually decelerated during a time interval of from t2 to t3 before stopping in this processing apparatus.
However, as shown in FIG. 8, a pulse laser beam having an irradiation energy Em is immediately emitted from the laser by turning the laser driving circuit on to initiate the irradiation at to which is repeated in response to a trigger frequency given to the laser driving circuit. The laser beam having a constant pulse width, repeating frequency and irradiation energy Em is always emitted from the laser, without being increased or decreased in contrast to the driving motor described above, until the laser driving circuit is turned off at t3 for ceasing the irradiation.
Accordingly, the laser beam irradiation density, per unit time and unit area on a beam irradiation surface of the work during the accelerating or decelerating travel period of the work, becomes larger than the beam irradiation density per unit time and unit area on the laser beam irradiation surface during the period at which the rotational velocity has reached to a given constant speed Sm in the processing method.
Consequently, the irradiation energy density per unit time and unit area of the laser beam irradiating at an initiation point 2a and a termination point 2b of the etching groove 2 (see FIGS. 9A and 9B) of the work 1 becomes larger than that irradiating the other portions. Therefore, when a half-etching processing with a given depth is to be applied on the work by using the excimer laser method, there is a drawback in that (1) the etching grooves at the processing initiation point 2a and processing termination point 2b of the etching groove 2 are formed deeper than the other portions, as shown in FIG. 9A, or (2) a hole is penetrated all through the depth of the work 1 at the processing initiation point 2a and termination point 2b of the etching groove 2, as shown in FIG. 9B.
When the work is to be cut off by the processing method using the CO2 laser and YAG laser, the quantity to be melted of the work 1 at a cutting initiation point 3a or termination point 3b of the cut-off site 3 of the work 1 becomes larger than that of the other cutting portions as shown in FIG. 9C, thereby resulting an error in the dimension, as well as burning and sticking of the cut-off site 3 at the initiation point 3a and termination point 3b. 
In order to obviate the aforementioned difficulties in the conventional processing method, the laser beam has been irradiated on the work merely within the time interval when rotation of the driving motor is stabilized by simply extending the overall driving time of the driving motor. In this case, the processing is started by initiating laser irradiation to the work with a timing later than the time t, when the rotational velocity of the driving motor has reached to a given speed Sm, and processing is completed by ceasing laser irradiation to the work with a timing prior to the time t2 when the rotational velocity of the driving motor initiates to reduce the speed from the given speed Sm as shown in FIG. 7.
However, the overall driving time T2 required for driving the driving motor largely exceed the maximum processing time T1 required for stable processing of the work as shown in FIG. 7 in the processing method as described above, causing a difficulty in that the substantial processing time of the work is unduely prolonged.
In addition, the difficulties such as the aforementioned dimensional error at the travel initiation point and termination point or non-uniform processing, or the substantially prolonged processing time may be caused by the laser beam irradiated only within the time interval when rotation of the driving motor has been stabilized. This may be encountered not only in the processing method and processing apparatus using the laser beam, but also in those using energy beams such as a light beam, x-ray beam and charged particle beam by which the degree of processing is changed depending on the energy density (area density) per unit time and per unit area of the irradiated beam.
Also, the above-mentioned difficulties may occur not only when the work is processed by allowing it to travel, but also when the work is processed by allowing the energy beam such as the laser beam to travel or when the work is processed by allowing the work and the energy beam to travel along different directions, respectively, crossing with each other.
Accordingly, the object of the present invention is to provide a processing method and processing apparatus therefor that allows a uniform processing with high accurate without prolonging the processing time.
In one aspect, the present invention provides a processing method by which a processing object is processed by being allowed to travel relative to an energy beam for irradiating the processing object, wherein the relative traveling velocity is made proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object relative to the energy beam is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object in the processing method as described above. Therefore, the irradiation energy density on the energy irradiation surface of the processing object within an accelerating region and decelerating region during the relative movement is equalized with the irradiation energy density on the energy irradiation surface of the processing object within the region where the relative traveling velocity has reached to a given constant speed, thereby allowing the irradiation energy density of the energy beam for irradiating the processing surface of the processing object to be uniform throughout the processing surface.
Also, the present invention provides a processing method by which the processing object is processed by being irradiated with an energy beam whose irradiation path is fixed relative to the traveling processing object, wherein the traveling velocity of the processing object relative to the energy beam is made proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object in the processing method as described above. Therefore, the irradiation energy density on the energy irradiation surface of the processing object within the accelerating region and decelerating region of the processing object is equalized with the irradiation energy density on the energy irradiation surface of the processing object within the region where the relative traveling velocity has reached to a given constant speed, thereby allowing the irradiation energy density of the energy beam for irradiating the processing surface of the processing object to be uniform throughout the processing surface.
Also, the present invention provides a processing method by which the processing object is processed by allowing the energy beam to travel relative to a fixed processing object, wherein the traveling velocity of the processing object relative to the energy beam is made proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object
The traveling velocity of the energy beam is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object in the processing method as described above. Therefore, the irradiation energy density on the energy irradiation surface of the processing object within the accelerating region and decelerating region of the energy beam is equalized with the irradiation energy density on the energy irradiation surface of the processing object within the region where the relative traveling velocity of the energy beam has reached to a given constant speed, thereby allowing the irradiation energy density of the energy beam for irradiating the processing surface of the processing object to be uniform throughout the processing surface.
Also, the present invention provides a processing method by which the processing object is processed by being allowed to travel along one direction of the two mutually orthogonal directions, along with allowing the energy beam for irradiating the processing object to travel along the other direction of the two directions, wherein the traveling velocity of the processing object relative to the energy beam is made to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object relative to the energy beam is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object in the processing method as described above. Therefore, the irradiation energy density on the energy irradiation surface of the processing object within the accelerating region and decelerating region of the relative traveling is equalized with the irradiation energy density on the energy irradiation surface of the processing object within the region where the relative traveling velocity has reached to a given constant speed, thereby allowing the irradiation energy density of the energy beam for irradiating the processing surface of the processing object to be uniform throughout the processing surface.
Also, the present invention provides a processing method in which the energy beam is a pulse energy beam having a given pulse width repeatedly irradiating the processing object, wherein the relative traveling velocity is made to be proportional to the repeating frequency of the energy beam.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object by allowing the relative traveling velocity to be proportional to the repeating frequency of the pulse energy beam having a given pulse width repeatedly irradiating the processing object in the processing method as described above.
Also, the present invention provides a processing method in which the energy beam is a pulse energy beam for repeatedly irradiating the processing object with a given repeating frequency, wherein the relative traveling velocity is made to be proportional to the pulse width of the energy beam.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object by allowing the relative traveling velocity to be proportional to the pulse width of the pulse energy beam repeatedly irradiating the processing object with a given repeating frequency in the processing method as described above.
The relative traveling velocity is preferably made to be proportional to the irradiation power of the energy beam in the processing method according to the present invention.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object by allowing the relative traveling velocity to be proportional to the irradiation power of the energy beam in the processing method as described above.
The energy beam is preferably a laser beam in the processing method according to the present invention.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit volume of the laser beam on the processing object in the processing method as described above.
In another aspect, the present invention provides a processing apparatus provided with processing object driving means for allowing a processing object to travel and an energy beam irradiation device for irradiating the energy beam on the processing surface of the processing object that is allowed to travel by the processing object driving means, wherein irradiation control means for controlling the energy beam irradiation device is provided so that the traveling velocity of the processing object relative to the energy beam is made to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object relative to the energy beam is adjusted to be proportional to the irradiation energy density per unit time and unit volume of the energy beam on the processing object by controlling the energy beam irradiation device with the irradiation control means in the processing apparatus as described above. Therefore, the energy density on the energy irradiation surface of the processing object within the acceleration region and deceleration region of the relative traveling is equalized with the irradiation energy density on the energy beam irradiation surface of the processing subject within the region where the relative traveling has reached to a given velocity, thereby allowing the irradiation energy density of the energy beam irradiating the processing surface of the processing object to be uniform throughout the processing surface.
In still another aspect of the present invention, a processing apparatus is provided with an energy beam irradiation device for irradiating the energy beam on the processing surface of the processing object and beam traveling means for allowing the energy beam to travel relative to the processing object, wherein an irradiation control means for controlling the energy beam irradiation device is provided so that the traveling velocity of the processing object relative to the energy beam is made to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object relative to the energy beam is made to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object in the processing device as described above. Therefore, the irradiation energy density per unit time and unit area of the energy beam on the processing object within accelerating and decelerating regions of the relative traveling is equalized with the irradiation energy density on the beam irradiation surface of the processing object within the region where the relative traveling has reached to a given velocity, thereby allowing the irradiation energy density of the energy beam irradiating the processing surface of the processing object to be uniform throughout the processing surface.
In yet another aspect of the invention, a processing apparatus is provided with processing object driving means for allowing the processing object to travel along one direction of mutually orthogonal two directions, an energy beam irradiation device for irradiating an energy beam on the processing surface of the processing object, and beam traveling means for allowing the energy beam to travel along the other direction of the two directions, wherein an irradiation control means for controlling at least one of the driving means and the energy beam irradiation device is provided so that the traveling velocity of the processing object relative to the energy beam is made to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
The traveling velocity of the processing object relative to the energy beam is adjusted to be proportional to the irradiation energy density per unit time and unit volume of the energy beam on the processing object in the processing apparatus as described above. Therefore, the irradiation energy density on the energy irradiation surface of the processing object within acceleration and deceleration regions of the relative traveling is equalized with the irradiation energy density on the irradiation surface of the processing object within the region where the relative traveling has reached to a given constant velocity, thereby allowing the irradiation energy density of the energy beam irradiating the processing surface of the processing object to be uniform throughout the processing surface.
Also, the present invention provides a processing apparatus using a device for repeatedly irradiating a pulse energy beam having a given pulse width on the processing object as the energy beam irradiation device, wherein the energy beam irradiation device is controlled so that the relative traveling velocity is made to be proportional to the repeating frequency of the energy beam.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit volume of the energy beam on the processing object by controlling the energy beam irradiation device for repeatedly irradiating the pulse energy beam having a given pulse width on the processing object with the irradiation control means so that the relative traveling velocity is made to be proportional to the repeating frequency of the energy beam in the processing apparatus as described above.
Also, the present invention provides a processing apparatus in which the irradiation control mean comprises synchronizing signal generation means for generating a synchronizing signal with a frequency proportional to the relative traveling velocity and trigger generation means that generates a driving trigger for driving the energy beam irradiation device in response to the synchronizing signal outputted from the synchronizing signal generation means at a frequency proportional to the relative traveling velocity.
The synchronizing signals with a frequency proportional to the relative traveling velocity is generated with the synchronizing signal generation means and the driving trigger with a frequency proportional to the relative traveling velocity is generated with the trigger generation means in response to the synchronizing signal in the processing apparatus as described above. Driving the energy beam irradiation device based on this driving trigger allows the relative traveling velocity to be proportional to the repeating frequency of the energy beam, thereby adjusting the relative traveling velocity to be proportional to the irradiation energy density per unit time and unit volume of the energy beam on the processing object.
Also, the present invention provides a processing apparatus provided with the processing object driving means constructed using a mounting table for mounting the processing object and a driving motor for allowing the mounting table along a given direction, wherein the irradiation control means is constructed using the synchronizing signal generation means for generating a synchronizing signal with a frequency proportional to the rotational velocity of the driving motor or the traveling velocity of the mounting table and the trigger generation means that generates the driving trigger for driving the energy beam irradiation device at a frequency proportional to the rotational velocity or to the traveling velocity in response to the synchronizing signal outputted from the synchronizing signal generation means.
The synchronizing signal with a frequency proportional to the rotational velocity of the driving motor or to the traveling velocity of the mounting table is generated with the synchronizing signal generation means and the driving trigger with a frequency proportional to the rotational velocity or traveling velocity is generated with the trigger generation means in response to the synchronizing signal in the processing apparatus as described above. Driving the energy beam irradiation device based on this driving trigger allows the rotational velocity of the driving motor or the traveling velocity of the mounting table to be proportional to the repeating frequency of the energy beam. Therefore, the traveling velocity of the processing object is allowed to be proportional to the repeating frequency of the energy beam, thereby allowing the traveling velocity of the processing object to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object.
Also, the present invention provides a processing apparatus using an encoder for generating pulse signals for given respective rotation angles of the driving motor, or a linear scale for generating pulse signals for given respective travel positions of the processing object as the synchronizing signal generation means.
The pulse signals for given respective rotation angles of the driving motor or corresponding to given respective travel positions of the processing object are generated as the synchronizing signals in the processing apparatus as described above. The trigger signal with a frequency proportional to the traveling velocity of the processing object is generated in response to the pulse signal from the linear scale.
The trigger generation means is preferably provided with a dividing circuit for dividing the synchronizing signal in the processing apparatus according to the present invention.
Dividing the synchronizing signal with the dividing circuit provided in the trigger generation means allows the driving trigger frequency for driving the energy beam irradiation device to be changed, thereby adjusting the irradiation energy density for irradiating the processing object.
Also, the present invention provides a processing apparatus using an irradiation means for repeatedly irradiating the pulse energy beam on the processing object at a repeating frequency as the energy beam irradiation device, wherein the energy beam irradiation device is controlled so that the relative traveling velocity is made to be proportional to the pulse width of the energy beam.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object by controlling the energy beam irradiation device that irradiates the pulse energy beam on the processing object at a given repeating frequency with the irradiation control means to allow the relative traveling velocity to be proportional to the pulse width of the energy beam in the processing apparatus as described above.
The energy beam irradiation device is preferably controlled so that the relative traveling velocity is made to be proportional to irradiation power of the energy beam.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the energy beam on the processing object by controlling the energy beam irradiation device with the irradiation control means to allow the relative traveling velocity to be proportional to the irradiation power of the energy beam in the processing apparatus as described above.
It is preferable that the energy beam is a laser beam in the processing apparatus according to the present invention.
The relative traveling velocity is adjusted to be proportional to the irradiation energy density per unit time and unit area of the laser beam on the processing object in the processing apparatus as described above.